Final answer:
The IT auditor should use the XCCDF schema within the SCAP framework to create and audit best practice configuration checklists and rules.
Step-by-step explanation:
The IT auditor should use the XCCDF (eXtensible Configuration Checklist Description Format) schema to develop and audit best practice configuration checklists and rules. XCCDF is a component of the Security Content Automation Protocol (SCAP), which IT auditors use to automate the process of checking system configuration against recognized best practice benchmarks. It allows for the structuring of specific security checklists and benchmarking materials, which can be universally understood and exchanged across different SCAP-compatible tools.